In our daily life, a hinge structure is implemented when two objects are required to be folded relative to each other. The hinge structure available presently generally consists of a male member and a female member. The male member generally includes a pivot shaft and a coupling portion while the female member includes a knuckle and a coupling portion. Under the normal condition, the pivot shaft extends rotatably into the knuckle while one object is mounted on the coupling portion. Another object is mounted on the coupling portion of female member such that the two objects can be folded onto or unfolded away from each other about an axis of the pivot shaft.
In actual practice, a positioning device is disposed between the pivot shaft and the knuckle in order to lock the male and female members together.
However, during locking operation of the pivot shaft within the knuckle, since the pivot shaft and the knuckle are mostly made from rigid materials, a flexible positioning device is generally implemented in order to absorb the distort deformation among the elements or the dimension interference. Thus, the flexible positioning device is subjected to suffer from wearing and flexible fatigue thereof. In other words, the service life of the conventional hinge structure is shortened consequently.